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Differences in pre-weaning mortality calculations

When you are reviewing reports from your record program do you know where the numbers come from and how they are calculated? When we look at records for the farrowing area we sometimes are puzzled by the numbers, especially pre-weaning mortality or pre-weaning death loss.

In this column we are going to look at three different pre-weaning death loss calculations. We selected 113 farms with 246,972 mated females from our Swine Management Services Farm In-depth Analysis database. The farm size ranges from 298 mated females to 7,052 mated females. There were 19,302,542 weaned pigs over the last three-year period included in this column. We use the following calculations to create the first three charts.

Pre-weaning mortality equals (pigs started for pre-wean mortality minus pigs weaned in period) divided by (pigs started for pre-wean mortality) multiplied by 100.

Recorded pre-weaning mortality equals recorded pig deaths divided by pigs started for pre-wean mortality multiplied by 100.

Chart 1 compares pre-weaning mortality (red line) to pre-weaning mortality with net foster (black line). The farm with the lowest pre-weaning mortality is on the left side of the chart and the farm with the highest pre-weaning mortality is on the right. When net fosters is not “0” the farm is creating pigs in the computer and pre-weaning mortality with net foster will be higher than your pre-weaning mortality. Pre-weaning mortality averages 12.5%, with a range of 4.3 to 19.2%. Pre-weaning mortality net foster averages 12.3%, with a range of 4.3 to 19.5%. The range for the difference in pre-weaning mortality with net foster and pre-weaning mortality by farms is -3.8% to 4.4%. The issue is only 28 of the 113 farms had records that had net fosters at “0” which is only 28.3% of the farms.

Chart 2 looks at the looks at the percent of (net foster divided by (pigs started for mortality minus pigs weaned)), black line, compared to pre-weaning mortality. The variation is large with the range being -44.5% to 44.3% and average -1.9%. The farm with the -44.5% net foster has a 9.3% pre-weaning mortality and a 5.4% pre-weaning mortality net foster. The problem is determining what the real number is and decided if management changes to be made improve pre-weaning mortality. On the other extreme the farm with the 44.3% net foster has a pre-weaning mortality of 10.1% and a pre-weaning mortality net foster of 13.9%. Again the problem is how to figure out what management changes are needed to lower pre-weaning mortality. One suggestion is to make sure whoever is doing the data entry checks the farrowing information for accuracy.

Chart 3 compares pre-weaning mortality (red line) to recorded pre-weaning mortality (black line). Recorded pre-weaning mortality is the information about each pig that dies in farrowing. The date of the death and the reason for each individual piglet death is recorded. Recorded pre-weaning mortality averages 12.1% with a range of 4.3 to 19.0%. The difference in pre-weaning mortality to recorded pre-weaning mortality is 0.5% with a range of -1.3 to 3.5%. Data shows that most farms are doing a good job of recording each individual piglet death. This number is probably a more accurate determination of the true pre-weaning mortality of the farm.

Chart 4 looks at recorded piglet losses by age; the average is 4.89 with a range of 0.4 to 21.72. There are six farms that record all the deaths on weaning day and two farms record all the deaths on farrowing day. We feel that recording piglet losses on the actual day is important and gives us good information for managing the farrowing house and developing standard operating procedures for Day 0-1 care, 46.4% of the deaths occurred during these two days. A total of 33.2% of deaths occurred during days 2-8 and 20.4% during days 9+. Management changes needed to lower piglet death losses in the farrowing house are different for losses occurring on days 0-1, 2-8 days and 9+ days. If day 1 pig care is being done correctly 60+% of the piglet deaths show up day 0-1 and piglet death loss after day 9+ should be less than 10%.

Do you know how accurate your pre-weaning mortality number is for your farm? It may be time to review how your crew is recording piglet deaths, how they handle fosters and what information is getting input in to your record program. In order to develop a plan to save more pigs in farrowing you need accurate information.

SMS Production Index
Table 1 provides the 52-week rolling averages for 11 production numbers represented in the SMS Production Index. The numbers are separated by 90-100%, the 70-90%, the 50-70%, the 30-50% and the 0-30% groups. We also included the 13-week, 26-week and 12-quarter averages. These numbers represent what we feel are the key production numbers to look at to evaluate the farm’s performance.

At SMS, our mission statement is to provide “Information solutions for the swine industry”. We feel with the creation of the new Farm Benchmarking database we now have more detailed information to share with the swine industry. If your farm would like to be part of the Farm Benchmarking database, or if you have suggestions on production areas to write columns about, email [email protected] or [email protected] or call us. We enjoy being a part of the National Hog Farmer Weekly Preview team.